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Stage 4 – What is Western Shield?
This stage introduces students to Western Shield and what it is designed to achieve.
Concepts
• Western Shield is the Department of Parks and Wildlife’s leading animal conservation program. The purpose of Western Shield is to protect wild populations of Western Australia’s threatened native animals through the control of foxes and feral cats.
• The control of introduced species to conserve native animals is a community concern requiring a landscape scale operation.
• Success can be achieved only after years of careful research and pioneer programs to test methods. • We can all help in bringing wildlife back from the brink of extinction.
Resources
❏ Stage 4 Resource sheet 4.1 – What is Western Shield (1 per group)
❏ Stage 4 Activity sheet 4.1 – What is Western Shield? Test your knowledge (1 per student) ❏ Stage 4 Activity sheet 4.2 – Western Shield story board
If time permits –
❏ Stage 4 Activity sheet extension 4.3 – Trap success ( for more advanced students)
Background information
Below is an expanded version of the Stage 4 Resource Sheet students will use. These additional details should help in answering student questions.
What’s all the fuss about?
Over the past 100 years, more mammals have become extinct in Australia than anywhere else in the world. In Western Australia, since European settlement:
• 12 mammal species have become extinct
• Seven species have disappeared from the mainland but remain on a few offshore islands • more than 40 species have declined significantly or are threatened with extinction.
The native mammals most at risk are small and medium sized animals weighing between 35 grams and 5.5 kilograms. This size animal is called a ‘critical weight range’ animal. Roughly, that equates to mouse size up to about medium sized cat size. Mammals are not the only animals under threat, birds and reptiles are under threat as well!
That’s not all—we don’t know what effect the loss of particular species will have on our environment, on the natural processes on which plants, animals and humans depend. The extinction or decline of any species is of great concern for a whole range of environmental, moral and aesthetic reasons.
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Is the problem real?
Some people would argue that the decline and disappearance of some animals from the bush isn’t real, that they are still out there just more secretive. Is this true?
Many methods can be used to determine what animals live in an area – trapping, sand pads, motion sensor camera, scat counts, spotlighting and burrow activity are some of the more common methods. Researchers have found that the population size and extent of occurrence for a number of species has decreased, particularly since European settlement. In many cases, species are no longer present in areas where they were known to once exist and their range has contracted to small pockets of remnant bushland. The decline in population size and occurrence of some species is not confined to particular areas but instead this has been the case for some animal species across the whole of Western Australia, and even Australia.
Researchers and most casual observers agree the decline is real and, for some animals, becoming critical. There is data to support the decline of many native species over time. Furthermore, the extinction of some animals from the wild since European settlement is undeniable truth that there is an issue for wildlife in Australia.
What is being done to halt the decline?
Research has identified many causes for the decline, some are easy to control, and other causes are much more difficult to control. One of the major causes of the decline in native animals is feral cats and foxes. Department of Parks and Wildlife (Parks and Wildlife) developed the Western Shield program to tackle these two introduced predators. Scientists observed that once introduced predator numbers were reduced, native animals then had a chance of increasing in numbers. Fail to control feral cats and foxes, and many threatened native animals are not able to build back up in number or extend to their former range!
What is Western Shield?
Western Shield is the Department of Parks and Wildlife’s leading animal conservation program. The
purpose of Western Shield is to protect wild populations of Western Australia’s threatened native animals through the control of foxes and feral cats. The aim is to bring threatened native animal wildlife back from the brink of extinction.
How does Western Shield work?
The first step of Western Shield is to monitor the ecosystem to determine what animals are present, both native and introduced, and at what numbers. A range of monitoring techniques can be used, dependent upon the habitat and level of information required. One commonly used measure is trapping success rate, which is essentially the number of traps that catch animals as a percentage of traps set. We monitor how this changes over time to get a trend for the population and this gives us an idea of whether the population is increasing, stable or declining. There is an extension activity available in this pack on trapping success rates for more able students.
If feral cats and foxes are present then controlling their numbers may be required. A range of factors need to be considered before a control method can be chosen. What geographical area is involved? What is the level of human use in the area? What natural features (vegetation, streams, and rocky
outcrops) occur in the area? Who are the neighbours and what is their livelihood? Which native animals are being affected? How critical is the drop in numbers?
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Conservation managers develop an appropriate control strategy for the area and its specific features based on research findings and advice.
One of the main control methods is the use of poison baits targeted at feral cats and foxes. Research revealed a poison that readily controls feral cats and foxes but posed a very low threat to our native animals. The poison, 1080 (pronounced ten-eighty) occurs naturally in the south-west of Western Australia so native animals have a high tolerance to 1080. A small sausage like meat bait, called
Probait®, is injected with 1080. These are readily eaten by foxes but cats are more cautious and usually only eat them when food is scarce. A specific cat bait, called Eradicat®, is currently being used for feral cat control. Both baits have been developed and are made by the Department of Parks and Wildlife. For some species which are prone to predation by foxes and feral cats, captive breeding is used but this is usually as a last resort. This could be done for a few reasons including to increase numbers of a species which might have suffered a significant decline as well as to preserve genetics of the existing population or populations. We need to deal with all threatening processes at a site including the possibility of fox and feral cat predation before captive bred animals are released back into the wild. For all ecosystems long term monitoring is required to look for changes in populations over
time. However, trapping success rates are influenced by more than just introduced predators. A corresponding record of weather, fire and other disturbances at a site needs to be made to check for other contributing factors to changes in trapping success rates.
Using nature to conserve nature
How can you use poison without harming our native animals? The answer lays in our natural advantage, Gastrolobium spp, also known as poison peas. Gastrolobium spp have sodium
monofluoroacetate, the technical name for 1080, in the leaves, flowers and seeds. Most Gastrolobium spp are found in the south-west of Western Australia. Over long periods of time our native animals have been exposed to this chemical and have developed a tolerance to sodiumfluoroacetate. So this means they have a very high tolerance. They are not immune to it though. Using research, the Department of Parks and Wildlife developed Probait®, a sausage like bait into which 1080 is injected. Probait® has enough 1080 to be deadly to foxes but under normal conditions harmless to our native animals here in Western Australia.
Eradicat® has recently been developed to specifically target feral cats who are much more fussy compared with foxes and do not readily take the probaits. The Eradicat® baits have extra additives to make them more enticing and palatable for feral cats. They also need to be used when there is more chance a feral cat is really hungry (i.e. when native animal activity is lower).
What happens if we use Probaits® or 1080 outside Western Australia? If poison peas are not found in the area being baited then the native animals do not generally have an increased tolerance to 1080 so can be more susceptible and may die. Table 1 on page 35 highlights the difference in tolerance level of native animals found on both sides of Australia, along with feral cat and fox tolerance.
Poison pea
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Tolerance (mg poison/Kg body weight)
Animal Western Australia Eastern States
Bobtail lizard 500 - 800 206 Bandicoot 20 7 Brushtail Possum 125 0.8 Chuditch/quoll 7.5 3.7 Bush rat 20-80 1.1 Grey kangaroo 40 0.3 Red kangaroo 2.5 2.5 Wedge-tailed eagle 9.5 9.5 Fox 0.13 0.13 Cat 0.35 0.35
Table 1 – 1080 Tolerance in Australian animals
Gastrolobium grandiflorum
Map 2 – Distribution of Poison pea plants and the concentration level of monofluoroacetate (ADS = air dry sample)
Acacia georginae (0-25mg/kg ADS)
Gastrobolobium grandiflorum (0-185mg/kg ADS) Gastrobolobium spp. (100-2650mg/kg ADS)
The 1080 baits have proven to be the most effective and appropriate management action to deal with foxes and feral cats at a landscape scale in Western Australia. Other toxins are being trialled for use in bates in Eastern Australia (e.g. PAPP or para-aminopropiophenome).
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Are there alternatives to poisoning? (for class discussion if required and /or appropriate)
A range of other techniques can be used to control feral cats and foxes including shooting and trapping. Shooting by licenced hunters requires a large amount of hours, mainly at night and is restricted to where shooters can reach by vehicle. The natural vegetation in some parts of the state, particularly the south west, is not well suited to shooting with vision restricted due to the density of plants. Using guns also has potentially deadly risks for humans as well. Animals also get wary near tracks and lights at night, so over time the effectiveness of shooting may decrease.
In some situations there is merit in shooting and trapping if it is done correctly and humanely. For the vast areas of Western Australia, 1080 has proven to be the most effective and appropriate management action to deal with foxes and feral cats at a landscape scale in Western Australia.
Is Western Shield working?
Western Shield aims to recover native animal populations in the wild through broad scale control of
foxes and feral cats. Here are some of the key successes and actions of the program to achieve fauna recovery: